In a radio signal communication system, information is transformed to radio signal for transmitting in form of an electromagnetic wave or radiation. These electromagnetic signals are further transmitted and/or received by suitable antennas.
In general, antennas are designed to work in particular frequency or frequency range. In some communication systems, the signal generators may generate electrical signals of multiple frequencies. Accordingly, multiple antennas operating in different operation frequencies or frequency ranges may be used to transmit and/or receive electromagnetic signals in different frequencies.